/*
 * @Descripttion: 
 * @Author: liuYaoYu
 * @Date: 2021-11-14 23:12:48
 * @LastEditors: liuYaoYu
 * @LastEditTime: 2021-11-14 23:14:53
 */
abstract class Animal {
    abstract sayHellow(n1: any, n2?: any, ...any: any[]): any
}

class Cat extends Animal {
    sayHellow() {

    }
}